Is RSV going around in the United States?

Respiratory syncytial virus (RSV) is a common respiratory virus that causes infections ranging from mild cold-like symptoms to serious lung disease. Almost all children get RSV by age two. In healthy adults and older children, RSV typically causes a mild to moderate cold. But in infants, older adults, and immunocompromised people, it can cause bronchiolitis, pneumonia, and hospitalization.

The RSV season in the United States typically runs from fall through early spring, with activity usually peaking between November and February. Since the COVID-19 pandemic, RSV patterns have become less predictable: seasons have shifted earlier or emerged outside their usual window in some years. The CDC's RSV-NET surveillance system tracks weekly hospital admission rates to identify when activity crosses into elevated ranges.

The highest-risk groups are premature infants, babies under six months old, and adults aged 60 and older. People with heart or lung disease, immune compromise, or other chronic conditions are also at elevated risk of severe RSV. In most healthy adults, RSV causes a cold-like illness that resolves on its own within one to two weeks.

Yes, as of 2023 the FDA has approved RSV vaccines for adults aged 60 and older and a maternal RSV vaccine for pregnant women. Additionally, nirsevimab (Beyfortus) is a long-acting monoclonal antibody recommended for infants entering their first RSV season. These interventions have significantly reduced the risk of severe RSV in the groups most likely to need hospital care.

RSV and influenza can cause similar-looking respiratory symptoms, but they are different viruses with different risk profiles. RSV disproportionately affects the very young and the very old, while flu affects all age groups, though it's still most severe in the elderly and those with chronic conditions. A laboratory test is usually needed to distinguish between them reliably. Both circulate simultaneously during the US winter respiratory season.